Laser processing device, laser processing temperature measuring device, laser processing method and laser processing temperature measuring method

ABSTRACT

The object is to provide a laser processing apparatus, a laser processing temperature measuring apparatus, a laser processing method, and a laser processing temperature measuring method which can highly accurately detect the processing temperature when carrying out processing such as welding with laser light. A laser processing apparatus  1 A for processing members. DR, UR to be processed by irradiating the members with laser light LB comprises a laser (semiconductor laser unit  20 A) for generating the laser light LB; optical means for converging the laser light LB generated by the laser onto processing areas DA, UA; and a filter  30 , disposed between the members DR, UR to be processed and the optical means, for blocking a wavelength of fluorescence generated by the optical means upon pumping with the laser light LB; wherein light having the wavelength blocked by the filter  30  is used for measuring a temperature of the processing areas DA, UA.

TECHNICAL FIELD

The present invention relates to a laser processing apparatus, a laserprocessing temperature measuring apparatus, a laser processing method,and a laser processing temperature measuring method which are useful formeasuring the temperature of a processing area when processing such aswelding is carried out with laser light.

BACKGROUND ART

Techniques for carrying out various kinds of processing such aspiercing, cutting, and welding by using laser light have conventionallybeen known. For example, Japanese Patent Publication No. HEI 5-42336discloses a method of bonding members with laser. In this method, on afirst thermoplastic resin member having a property of absorbing laserlight of a YAG laser, a second thermoplastic resin member having aproperty of transmitting the laser light therethrough is overlaid. Then,the YAG laser irradiates the first thermoplastic resin member with thelaser light by way of the second thermoplastic rein member, so as toheat and melt the first thermoplastic resin member, thereby welding thefirst and second thermoplastic resin members to each other.

When carrying out processing with laser light, it is important that thetemperature in the processing area be controlled in order to prevent theprocessing from becoming defective. For detecting the temperature of theprocessing area, a radiation thermometer, which uses the light thermallyradiating from the processing area, or the like is employed. Forexample, Japanese Patent Application Laid-Open No. HEI 5-261576discloses a heat processing apparatus which regulates the surfacetemperature of a subject to be processed when welding the subject withlaser light. In this heat processing apparatus, the light thermallyradiating from the surface of the subject to be processed is dividedinto a plurality of light components, which are then transmitted throughvarious filters adapted to transmit respective wavelength lightcomponents therethrough. A surface temperature is detected from theintensity ratio of various wavelength light components transmittedthrough the filters, and the surface temperature of the subject to beprocessed is controlled according to thus detected surface temperature.

DISCLOSURE OF THE INVENTION

When welding resin members to each other with laser light, however,there have been cases where the welding temperature cannot be detectedaccurately, and thus cannot be regulated normally, whereby defectivewelding has occurred. For welding with laser in particular, not onlysolid lasers such as YAG laser, but also semiconductor lasers with anincreased output have come into use. In the case where a semiconductorlaser is used for welding resin members to each other, the weldingtemperature cannot be detected accurately when the temperature of thewelding area is detected by a radiation thermometer. The detection ofthe welding temperature in the welding of resin members to each other isnot mentioned at all in Japanese Patent is Application Laid-Open No. HEI5-261576.

It is therefore an object of the present invention to provide a laserprocessing apparatus, a laser processing temperature measuringapparatus, a laser processing method, and a laser processing temperaturemeasuring method which can highly accurately detect the processingtemperature when carrying out processing such as welding with laserlight.

In one aspect, the present invention provides a laser processingapparatus for processing a member to be processed by irradiating themember with laser light, the apparatus comprising a laser for generatinglaser light; optical means for converging the laser light generated bythe laser onto a processing area; and a filter, disposed between themember to be processed and the optical means, for blocking a wavelengthof fluorescence generated by the optical means upon pumping with thelaser light; wherein light having the wavelength blocked by the filteris used for measuring a temperature of the processing area.

In the fluorescence generated by the optical means, light having awavelength which becomes an observation wavelength for measuring theprocessing temperature is removed by the filter in this laser processingapparatus before processing. Therefore, a fluorescence component havinga wavelength identical to the observation wavelength generated by theoptical means does not radiate from the processing area. Hence, when alight component having the wavelength removed by the filter in lightthermally radiating from the processing area is used, the temperature ofthe processing area can accurately be detected without being affected bynoise light caused by the fluorescence of the optical means.

In another aspect, the present invention provides a laser processingapparatus for processing a member to be processed by irradiating themember with laser light, the apparatus comprising a laser for generatinglaser light; first optical means for converging the laser lightgenerated by the laser onto a processing area; and second optical means,disposed between the member to be processed and the first optical means,for blocking a wavelength of fluorescence generated by the optical meansupon pumping with the laser light; wherein light having the wavelengthblocked by the second optical means is used for measuring a temperatureof the processing area.

In the fluorescence generated by the first optical means, light having awavelength which becomes an observation wavelength for measuring theprocessing temperature is removed by a coating applied to the secondoptical means for suppressing the reflection loss or the like in thislaser processing apparatus before processing. Therefore, a fluorescencecomponent having a wavelength identical to the observation wavelengthgenerated by the first optical means does not radiate from theprocessing area. Hence, when a light component having the wavelengthremoved by the second optical means in light thermally radiating fromthe processing area is used, the temperature of the processing area canaccurately be detected without being affected by noise light caused bythe fluorescence of the first optical means.

The laser processing apparatus in accordance with the above-mentionedaspects of the present invention may be configured such that the filteror second optical means blocks a wavelength other than an oscillationwavelength of the laser light.

Since this laser processing apparatus totally removes light having awavelength other than the oscillation wavelength unnecessary forprocessing in the fluorescence generated by the optical means before theprocessing, the light radiating from the processing area does notinclude the fluorescence generated by the optical means at all.

In still another aspect, the present invention provides a laserprocessing temperature measuring apparatus for measuring the temperatureof the processing area being processed by the above-mentioned laserprocessing apparatus, the measuring apparatus comprising temperaturedetecting means for detecting the temperature according to a lightcomponent having the wavelength blocked by the filter or second opticalmeans in light thermally radiating from the processing area.

This laser processing temperature measuring apparatus can detect theprocessing temperature with a high accuracy, since the temperaturedetecting means can detect the processing temperature by using thermallyradiating light without any mingling noise light (part or whole offluorescence) generated by the optical means as light having theobservation wavelength.

In still another aspect, the present invention provides a laserprocessing method for processing a member to be processed by irradiatingthe member with laser light; the method comprising a laser lightgenerating step of generating laser light; a light-converging step ofcausing an optical system to converge the laser light generated by thelaser light generating step onto a processing area; and a fluorescenceblocking step of causing a filter to block a wavelength of fluorescencegenerated by the optical system upon pumping with the laser light beforeprocessing; wherein light having the wavelength blocked by thefluorescence blocking step is used for measuring a temperature of theprocessing area.

In the fluorescence generated by the optical system, light having awavelength which becomes an observation wavelength for measuring theprocessing temperature is removed by the filter in this laser processingmethod before processing, whereby the temperature of the processing areacan accurately be detected according to thermally radiating light freeof noise light mingling therein.

In still another aspect, the present invention provides a laserprocessing method for processing a member to be processed by irradiatingthe member with laser light; the method comprising a laser lightgenerating step of generating laser light; a light-converging step ofcausing a first optical system to converge the laser light generated bythe laser light generating step onto a processing area; and afluorescence blocking step of causing a second optical system to block awavelength of fluorescence generated by the first optical system uponpumping with the laser light before processing; wherein light having thewavelength blocked by the fluorescence blocking step is used formeasuring a temperature of the processing area.

In the fluorescence generated by the first optical system, light havinga wavelength which becomes an observation wavelength for measuring theprocessing temperature is removed by a coating applied to the secondoptical means for suppressing the reflection loss or the like in thislaser processing method before processing, whereby the temperature ofthe processing area can accurately be detected according to thermallyradiating light free of noise light mingling therein.

In still another aspect, the present invention provides a laserprocessing temperature measuring method for measuring the temperature ofthe processing area being processed by the laser processing method inaccordance with the above-mentioned aspects, the measuring methodcomprising a temperature detecting step of detecting the temperatureaccording to a light component having the wavelength blocked by thefluorescence blocking step in light thermally radiating from theprocessing area.

This laser processing temperature measuring method can detect theprocessing temperature with a high accuracy, since the processingtemperature can be detected by using thermally radiating light withoutany mingling noise light (part or whole of fluorescence) generated bythe optical system as light having the observation wavelength.

In still another aspect, the present invention provides a laserprocessing apparatus for welding resin members to each other by usinglaser light, the apparatus comprising a semiconductor laser forgenerating laser light; and a filter, disposed between the semiconductorlaser and the resin members, for blocking light having a wavelength tobecome an observation wavelength for measuring a temperature of awelding area in the light generated by the semiconductor laser; whereinlight having the wavelength blocked by the filter is used for measuringthe temperature of the welding area.

In the light generated by the semiconductor laser, a light componenthaving a wavelength which becomes an observation wavelength formeasuring the welding temperature is removed by the filter beforewelding in this laser processing apparatus. Therefore, a light componenthaving a wavelength identical to the observation wavelength generated bythe semiconductor laser does not radiate from the welding area(processing area). Hence, when a light component having the wavelengthremoved by the filter in the light thermally radiating from the weldingarea is used, the temperature of the welding area (processingtemperature) can accurately be detected without being affected by noiselight caused by the semiconductor laser.

In still another aspect, the present invention provides a laserprocessing apparatus for welding resin members to each other by usinglaser light, the apparatus comprising a semiconductor laser forgenerating laser light; and optical means for converging the laser lightgenerated by the semiconductor laser onto a welding area and blockinglight having a wavelength to become an observation wavelength formeasuring a temperature of the welding area in the light generated bythe semiconductor laser; wherein light having the wavelength blocked bythe optical means is used for measuring the temperature of the weldingarea.

In the light generated by the semiconductor laser, a light componenthaving a wavelength which becomes an observation wavelength formeasuring the welding temperature is removed by a coating applied to theoptical means for suppressing the reflection loss or the like beforewelding in this laser processing apparatus. Therefore, a light componenthaving a wavelength identical to the observation wavelength generated bythe semiconductor laser does not radiate from the welding area. Hence,when a light component having the wavelength removed by the opticalmeans in the light thermally radiating from the welding area is used,the temperature of the welding area can accurately be detected withoutbeing affected by noise light caused by the semiconductor laser.

The laser processing apparatus in accordance with the above-mentionedaspects of the present invention may be configured such that the filteror optical means blocks light having a wavelength other than anoscillation wavelength of the semiconductor laser.

Since this laser processing apparatus totally removes the lightcomponent having a wavelength other than the oscillation wavelengthunnecessary for welding in the light generated by the semiconductorlaser, the light radiating from the welding area does not include lightother than the oscillation wavelength generated by the semiconductorlaser at all.

The laser processing apparatus in accordance with the above-mentionedaspects of the present invention may be configured such that the filteror optical means blocks light having a wavelength falling within therange of 1100 nm to 2800 nm.

This laser processing apparatus removes light having a wavelengthfalling within the range of 1100 nm to 2800 nm, which is a wavelengthrange suitable for detecting the welding temperature in the lightgenerated from the semiconductor laser, before welding, whereby thelight radiating from the welding area does not include any noise lightfor detecting the welding temperature generated by the semiconductorlaser. Here, the welding temperature detected by light having awavelength shorter than 1100 nm is hard to weld the welding members toeach other. On the other hand, light having a wavelength longer than2800 nm cannot be transmitted through the resin members, and thus cannotbe used for detecting the welding temperature when welding the resinmembers to each other in a stacked fashion.

In still another aspect, the present invention provides a laserprocessing temperature measuring apparatus for measuring the temperatureof the welding area being welded by the laser processing apparatus inaccordance with the above-mentioned aspects of the present invention,the measuring apparatus comprising temperature detecting means fordetecting the temperature according to a light component having thewavelength blocked by the filter or optical means in light thermallyradiating from the welding area.

This laser processing temperature measuring apparatus can detect thewelding temperature (processing temperature) with a high accuracy, sincethe temperature detecting means can detect the processing temperature byusing thermally radiating light without any mingling noise light (partor whole of light other than the oscillation wavelength) generated bythe semiconductor laser as light having the observation wavelength.

In still another aspect, the present invention provides a laserprocessing method for welding resin members to each other by using laserlight, the method comprising a laser light generating step of causing asemiconductor laser to generate laser light; and a filtering step ofblocking light having a wavelength to become an observation wavelengthfor measuring a temperature of a welding area in the light generated bythe laser light generating step with a filter before welding; whereinlight having the wavelength blocked by the filtering step is used formeasuring the temperature of the welding area.

In the light generated by the semiconductor laser, a light componenthaving a wavelength which becomes an observation wavelength formeasuring the welding temperature is removed by the filter beforewelding in this laser processing method, whereby the temperature of thewelding area can accurately be detected according to thermally radiatinglight free of noise light mingling therein.

In still another aspect, the present invention provides a laserprocessing method for welding resin members to each other by using laserlight, the method comprising a laser light generating step of causing asemiconductor laser to generate laser light; and a filtering step ofblocking light having a wavelength to become an observation wavelengthfor measuring a temperature of a welding area in the light generated bythe laser light generating step with an optical system adapted toconverge the laser light generated by the laser light generating steponto the welding area; wherein light having the wavelength blocked bythe filtering step is used for measuring the temperature of the weldingarea.

In the light generated by the semiconductor laser, a light componenthaving a wavelength which becomes an observation wavelength formeasuring the welding temperature is removed by a coating applied to theoptical system for suppressing the reflection loss or the like in thislaser processing method before welding, whereby the temperature of thewelding area can accurately be detected according to thermally radiatinglight free of noise light mingling therein.

In stilt another aspect, the present invention provides a laserprocessing temperature measuring method for measuring the temperature ofthe welding area being welded by the laser processing method inaccordance with the above-mentioned aspects of the present invention,the measuring method comprising a temperature detecting step ofdetecting the temperature according to a light component having thewavelength blocked by the filtering step in light thermally radiatingfrom the welding area.

This laser processing temperature measuring method can detect thewelding temperature with a high accuracy, since it can detect thewelding temperature by using thermally radiating light without anymingling noise light (part or whole of light other than the oscillationwavelength) generated by the semiconductor laser as light having theobservation wavelength.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall diagram of the resin welding apparatus inaccordance with first and fourth embodiments of the present invention;

FIG. 2 is a side view of the semiconductor laser unit and first cutfilter in the resin welding apparatus in accordance with the firstembodiment;

FIG. 3 is a chart showing relationships between the wavelength andintensity of noise light emitted from semiconductor laser units;

FIG. 4 is a chart showing relationships between the wavelength of lightand the transmittance of light in the resin members when the resinmembers are irradiated with light;

FIG. 5 is a chart showing relationships between wavelength and intensityin laser light having an oscillation wavelength and additional lightemitted from a semiconductor laser unit, and thermally radiating lightgenerated by a welding area;

FIG. 6 is a chart showing relationships between wavelength and intensityin laser light having an oscillation wavelength and additional lightemitted from the semiconductor laser unit shown in FIG. 1;

FIG. 7 is a chart showing the relationship between wavelength andtransmittance as a characteristic of the first cut filter shown in FIG.1;

FIG. 8 is a chart showing the relationship between wavelength andintensity of light obtained after the light emitted from thesemiconductor laser unit shown in FIG. 1 is transmitted through thefirst cut filter;

FIG. 9 is a chart showing the relationship between wavelength andintensity of light radiating from the welding areas shown in FIG. 1;

FIG. 10 is a chart showing the relationship between wavelength andtransmittance as a characteristic of the second cut filter shown in FIG.1;

FIG. 11 is a chart showing the relationship between wavelength andintensity of light obtained after the light radiating from the weldingareas shown in FIG. 1 is transmitted through the second cut filter;

FIG. 12 is an overall diagram of the resin welding apparatus inaccordance with second and fifth embodiments of the present invention;

FIG. 13 is a side view of the semiconductor laser unit and first cutfilter in the resin welding apparatus in accordance with the secondembodiment;

FIG. 14 is an overall diagram of the resin welding apparatus inaccordance with third and sixth embodiments of the present invention;

FIG. 15 is a side view of the semiconductor laser unit in the resinwelding apparatus in accordance with the third embodiment;

FIG. 16 is a chart showing the relationship between wavelength andtransmittance as a characteristic of a coating of the condenser lensshown in FIG. 15;

FIG. 17 is a chart showing the relationship between wavelength andintensity of light obtained after the light emitted from thesemiconductor laser unit shown in FIG. 14 is transmitted through thecondenser lens;

FIG. 18 is a chart showing relationships between wavelength andintensity of light radiating from the welding areas shown in FIG. 14;

FIG. 19 is a chart showing the relationship between wavelength andtransmittance as a characteristic of the bandpass filter shown in FIG.14;

FIG. 20 is a chart showing the relationship between wavelength andintensity of light obtained after light radiating from the welding areasshown in FIG. 14 is transmitted through the bandpass filter;

FIG. 21 is a side view of the semiconductor laser unit and first cutfilter in the resin welding apparatus in accordance with the fourthembodiment;

FIG. 22 is a side view of the semiconductor laser unit and first cutfilter in the resin welding apparatus in accordance with the fifthembodiment; and

FIG. 23 is a side view of the semiconductor laser unit in the resinwelding apparatus in accordance with the sixth embodiment.

BEST MODES FOR CARRYING OUT THE INVENTION

In the following, embodiments of the laser processing apparatus, laserprocessing temperature measuring apparatus, laser processing method, andlaser processing temperature measuring method in accordance with thepresent invention will be explained with reference to the drawings.

For highly accurately detecting the processing temperature when carryingout various kinds of processing with laser, the present inventionprevents noise light from mingling into light thermally radiating from aprocessing area.

In one aspect, the present invention finds out that there is a casewhere the noise light includes fluorescence generated by an opticalsystem for converging laser light, and removes a light component havinga wavelength to become an observation wavelength for detecting theprocessing temperature in the fluorescence generated by the opticalsystem before processing. To this aim, the present invention uses afilter or (a coating or the like of) an optical system such as acondenser lens for laser, so as to block light having the wavelength tobecome the observation wavelength.

In another aspect, the present invention finds out that there is a casewhere the noise light includes a light component other than anoscillation wavelength generated by a semiconductor laser, and removes alight component having a wavelength to become an observation wavelengthfor detecting a welding temperature in light generated by thesemiconductor laser before welding. To this aim, the present inventionuses a filter or an optical system such as a condenser lens for laser,so as to block light having the wavelength to become the observationwavelength.

In an embodiment, the present invention is employed in a resin weldingapparatus for welding resin members to each other in a stacked fashionby using laser light. The resin welding apparatus in accordance withthis embodiment comprises a semiconductor laser unit for emitting laserlight and a resin temperature measuring apparatus for detecting awelding temperature of a welding area, and controls the weldingtemperature according to the welding temperature detected by the resintemperature measuring apparatus.

First to third embodiments relate to cases where the noise lightincludes fluorescence generated by the optical system for converging thelaser light. In the first and second embodiments, the fluorescencegenerated by optical means of the semiconductor laser unit is cut by acut filter. In particular, the first embodiment uses a semiconductorlaser unit of direct focusing type, whereas the second embodiment uses asemiconductor laser unit of fiber-out type. In the third embodiment, acoating applied to a condenser lens of a semiconductor laser unit (ofdirect focusing type) partly cuts the fluorescence.

Fourth to sixth embodiments relate to cases where the noise lightincludes a light component other than an oscillation wavelengthgenerated by a semiconductor laser. In the fourth and fifth embodiments,the light component other than the oscillation wavelength generated bythe semiconductor laser unit is cut by a cut filter. In particular, thefourth embodiment uses a semiconductor laser unit of direct focusingtype, whereas the fifth embodiment uses a semiconductor laser unit offiber-out type. In the sixth embodiment, a coating applied to acondenser lens of a semiconductor laser unit (of direct focusing type)partly cuts the fluorescence.

FIRST EMBODIMENT

Initially, the first embodiment will be explained. With reference toFIG. 1, the configuration of a resin welding apparatus 1A will beexplained. FIG. 1 is an overall diagram of the resin welding apparatus1A in accordance with the first embodiment.

The resin welding apparatus 1A is an apparatus which controls thewelding temperature so as to make it fall within a reference temperaturerange, and welds an upper resin member UR (e.g., acrylic resin) and alower resin member DR (e.g., ABS resin), which are members to be welded,to each other in a stacked fashion while pressing them. To this aim, theresin welding apparatus 1A comprises a pressure applying unit 10, asemiconductor laser unit 20A, a first cut filter 30, a second cut filter40, a resin temperature measuring unit 50A, a robot arm unit 60, and acontrol unit 70.

The upper resin member UR has a property of transmitting therethroughlaser beams LB having an oscillation wavelength of the semiconductorlaser unit 20A. On the other hand, the lower resin member DR has aproperty of absorbing the laser beams LB having the oscillationwavelength of the semiconductor laser unit 20A. Therefore, in the resinwelding apparatus 1A, the laser beams LB emitted from the semiconductorlaser unit 20A are transmitted through the upper resin member UR, andare absorbed by an area (welding area) DA to be welded to the upperresin member UR in the surface of the lower resin member DR. Thisabsorption heats and melts the welding area DA. This heat melts an area(welding area) UA to be welded in the surface of the upper resin memberUR, whereby the upper resin member UR and the lower resin member DR arewelded to each other.

The pressure applying unit 10 presses the upper resin member UR andlower resin member DR. When melting the welding area DA by heating, theheat will be hard to conduct to the welding area UA if a gap existsbetween the welding regions DA and UA. As a consequence, defectivewelding may occur. Therefore, the pressure applying unit 10 presses thewelding areas DA and UA to each other so as to bring them, into closecontact with each other.

The pressure applying unit 10 comprises a base plate 11, a pressureplate 12, regulators 13, 13, and a controller 14. The lower resin memberDR is mounted on the upper face of the base plate 11, whereas the upperresin member UR is mounted on the upper face of the lower resin memberDR. The pressure plate 12 is constructed by a material adapted totransmit the laser beam LB therethrough, and is disposed above the baseplate 11. The pressure plate 12 presses the lower resin member DR andresin member UR stacked on the base plate 11. The regulators 13, 13 movethe pressure plate 12 up and down according to a control signal from thecontroller 14, thereby regulating the distance between the base plate 11and pressure plate 12. According to an instruction signal from thecontrol unit 70, the controller 14 sends a control signal forcontrolling the pressure so as to make it fall within a referencepressure range.

With reference to FIG. 2 as well, the semiconductor laser unit 20A willbe explained. FIG. 2 is a side view of the semiconductor laser unit 20Aand first cut filter 30.

The semiconductor laser unit 20A irradiates the welding area DA with thelaser beams LB (having an oscillation wavelength of 810 nm), so as toheat and melt the upper resin member UR and lower resin member DR. Tothis aim, the semiconductor laser unit 20A comprises a main unit 21 anda controller 22. The main unit 21 generates the laser beam LB accordingto a control signal from the controller 22, converges thus generatedlaser beams LB, and emits them toward the welding area DA. According toinstruction signals from the control unit 70, the controller 22 sendscontrol signals for regulating irradiation conditions (intensity, focusdiameter, etc.) to the main unit 21.

The main unit 21 comprises a semiconductor laser 21 a, first collimatinglenses 21 b, . . . , a second collimating lens 21 c, and a condenserlens 21 d. The semiconductor laser 21 a includes planar electrodes 21 e,21 f, whereas a plurality of laser arrays 21 h, . . . are laminatedbetween the planar electrodes 21 e, 21 f by way of heat sinks 21 g, . .. , so as to form a laser array stack. Each laser array 21 h has astructure in which a plurality of laser light emission points 21 i, . .. are arranged in a row, whereas the laser light emission points 21 i,.. . emit the respective laser beams LB. The first collimating lenses 21b, second collimating lens 21 c, and condenser lens 21 d act as opticalmeans for converging the laser beams LB generated by the semiconductorlaser 21 a onto the welding area DA.

For each laser array 21 h, the first collimating lens 21 b is arrangedin front of the laser array 21 h in the emitting direction of the laserbeam LB while in parallel with the laser array 21 h. The firstcollimating lens 21 b is a cylindrical lens, and converges therespective laser beams LB emitted from the laser light emission points21 i of the laser array 21 h into the latitudinal direction of the laserarray 21 h (i.e., the direction in which the laser light emission points21 i of the semiconductor laser 21 a are arranged).

For each row of the laser light emission points 21 i, . . . in thelaminating direction of the lens arrays 21 h, . . . , the secondcollimating lens 21 c is arranged in front of the first collimatinglenses 21 b, . . . in the emitting direction of the laser beam LB whilein parallel with the laser emission points 21 i, . . . arranged in a rowin the laminating direction of the laser arrays 21 h, . . . . The secondcollimating lens 21 c is a columnar convex lens, and converges therespective laser beams LB emitted from the laser light emission points21 i into the longitudinal directions of the laser arrays 21 h.

The condenser lens 21 d is disposed in front of the second collimatinglens 21 c in the emitting direction of the laser beams LB. The condenserlens 21 d has a predetermined focal length, and converges parallel lightonto a focal point (welding area DA).

The main unit 21 generates a voltage between the planar electrodes 21 e,21 f according to a control signal from the controller 22, and emits therespective laser beams LB from the laser light emission points 21 iaccording to this voltage. In the main unit 21, the laser beams LBemitted from the laser light emission points 21 i are turned intoparallel beams with respect to the latitudinal directions of the laserarrays 21 h by the first collimating lenses 21 b, and then are turnedinto parallel beams with respect to the longitudinal directions of thelaser arrays 21 h by the second collimating lens 21 c. Finally, in themain unit 21, the laser beams LB turned into parallel light areconverged onto the welding area DA by the condenser lens 21 d.

As in the foregoing, the semiconductor laser unit 20A is a high-outputlaser unit which emits a number of laser beams LB from the respectivelaser light emission points 21 i and collects the laser beams LB. Thesemiconductor laser unit 20A is of direct focusing type in which themain unit 21 converges the laser beams. LB and directly emits them tothe welding area DA. In the semiconductor laser unit 20A, the verticalposition of the main unit 21 is movable by the robot arm unit 60, sothat the focal position of the laser beams LB is adjusted. Also, in thesemiconductor laser unit 20A, the horizontal position of the main unit21 is movable by the robot arm unit 60, so that the welding speed andwelding position are adjusted.

Here, the facts elucidated by experiments about the semiconductor laserunit will be explained with reference to FIG. 3. FIG. 3 is a chartshowing relationships between the wavelength and intensity of additionallight (fluorescence here) emitted from semiconductor laser units. In thedrawings and specification, “additional light” refers to lightcomponents other than the oscillation wavelength of the semiconductorlaser in the light generated by each semiconductor laser unit.

A semiconductor laser unit is configured so as to emit laser lighthaving a single oscillation wavelength (e.g., 810 nm). However, variousexperiments have elucidated that the semiconductor laser unit emitsadditional light as well. FIG. 3, whose abscissa and ordinate indicatewavelength and light intensity, respectively, shows intensity vs.wavelength characteristics of additional light components emitted fromrespective semiconductor laser units having oscillation wavelengths of810 nm and 920 nm. As can be seen from FIG. 3, each semiconductor laserunit emits additional light (infrared light) from 1300 nm to 2100 nm onthe longer wavelength side of the oscillation wavelength regardless ofwhere the oscillation wavelength is. The intensity of this additionallight drastically increases from near 1300 nm to near 1400 nm andgradually decreases from near 1400 nm. The intensity of the additionallight is lower than that of the laser light having the oscillationwavelength by at least 6 digits.

One of reasons why a semiconductor laser unit emits additional light isthe generation of fluorescence in optical means such as first and secondcollimating lenses and a condenser lens in the semiconductor laser unit.This is because these optical means absorb the laser light emitted bythe semiconductor laser and thus attain an excited state, therebygenerating fluorescence having a wavelength longer than the oscillationwavelength of the laser light. For example, the semiconductor laser unit20A in accordance with the first embodiment emits the laser beams LBhaving an oscillation wavelength (810 nm) and fluorescence, which isadditional light, as shown in FIG. 6. FIG. 6, whose abscissa andordinate indicate the wavelength and intensity of light, respectively,is a chart showing relationships between wavelength and intensity inlaser light having an oscillation wavelength and additional light(fluorescence here) emitted from the semiconductor laser unit.

With reference to FIG. 4, characteristics of resin members will also beexplained. FIG. 4 is a chart showing relationships between thewavelength of light and the transmittance of light in the resin memberswhen the resin members are irradiated with light.

FIG. 4, whose abscissa and ordinate indicate the wavelength of lightirradiating the resin members and the transmittance of light in theresin members, respectively, shows respective characteristics of fiveresin members, i.e., ABS resin (white), polyvinyl chloride(transparent), polyethylene terephthalate (transparent), polycarbonate(transparent), and acrylic resin (transparent). As can be seen from FIG.4, each of the five resin members has a property of hardly transmittingtherethrough light having a wavelength longer than 2800 nm. Therefore,radiation thermometers cannot use the thermally radiating light having awavelength longer than 2800 nm for detecting the welding temperature instacked welding, since they detect the welding temperature by usingthermally radiating light transmitted through the upper resin member.

When welding resin members to each other, the welding temperature is aslow as 200° to 400° C., whereby it is necessary to use thermallyradiating light having a wavelength longer than 1100 nm in order for aradiation thermometer to detect the welding temperature from thermallyradiating light having a low temperature of about 200° C. Therefore,when detecting the welding temperature in stacked welding, it isnecessary for the radiation thermometer to use a wavelength within therange of 1100 nm to 2800 nm as an observation wavelength.

With reference to FIG. 5, the relationship between the wavelengths ofthermally radiating light and additional light and the observationwavelength in the case where stacked welding is carried out by asemiconductor laser unit will also be explained. FIG. 5 is a chartshowing relationships between wavelength and intensity in laser lighthaving an oscillation wavelength and additional light (fluorescencehere) emitted from the semiconductor laser unit, and thermally radiatinglight generated by a welding area.

FIG. 5, whose abscissa and ordinate indicate the wavelength andintensity of light, respectively, shows respective characteristics ofthe laser light having the oscillation wavelength (810 nm), fluorescencewhich is the additional lights and thermally radiating light. As can beseen from FIG. 5, the fluorescence and the thermally radiating lighthave respective output characteristics overlapping each other within thewavelength range of 1400 nm to 2100 nm The intensity of fluorescence islower than that of the above-mentioned laser light having theoscillation wavelength by at least 6 digits. When welding resin membersto each other, the welding temperature is low, whereby the intensity ofthermally radiating light is so low as to be influenced by thefluorescence. When welding resin members to each other in a stackedfashion, a wavelength within the range of 1100 nm to 2800 nm is used asthe observation wavelength of the radiation thermometer as mentionedabove. Therefore, when detecting the welding temperature in stackedwelding of the resin members to each other, it seems that the radiationthermometer has conventionally been incapable of accurately detectingthe welding temperature from the thermally radiating light, since thefluorescence, which is additional light emitted from the semiconductorlaser unit, becomes noise light for the thermally radiating light aswell.

Hence, no noise light will mingle into the thermally radiating light ifthe light having the observation wavelength used for detectingtemperature in the radiation thermometer in the fluorescence generatedby the semiconductor laser unit is removed before welding. In this case,noise light can reliably be excluded if the fluorescence is totallyremoved or light falling within the observation wavelength range of theradiation thermometer, i.e., 1100 nm to 2800 nm, is removed.

Returning to the explanation of the configuration of the resin weldingapparatus 1A, the first cut filter 30 will be explained with referenceto FIGS. 2, 7, and 8 as well. FIG. 7 is a chart showing the relationshipbetween wavelength and transmittance as a characteristic of the firstcut filter 30. FIG. 8 is a chart showing the relationship betweenwavelength and intensity of light obtained after the light emitted fromthe semiconductor laser unit 20A is transmitted through the first cutfilter 30.

The first cut filter 30 is a filter which totally cuts fluorescent beamsFB emitted from the semiconductor laser unit 20A before welding. FIG. 7,whose abscissa and ordinate indicate wavelength and transmittance,respectively, shows a transmission characteristic (solid line) of thefirst cut filter 30. As can be seen from FIG. 7, the first cut filter 30has a property of transmitting therethrough light having a wavelengthshorter than 1200 nm (i.e., a property of totally blocking noise light)in order to transmit therethrough the laser beams LB having theoscillation wavelength of 810 nm and block the fluorescent beams FBacting as additional light. When the laser beams LB and fluorescentbeams FB emitted from the semiconductor laser unit 20A enter the firstcut filter 30 having such a property, only the laser beams LB having theoscillation wavelength are transmitted therethrough as shown in FIG. 8.In FIG. 8, the abscissa and ordinate indicate the wavelength andintensity of light, respectively.

The first cut filter 30 is disposed at a position between the main unit21 of the semiconductor laser unit 20A and the upper resin member UR,where the laser beams LB and fluorescent beams FB pass, and isconfigured so as to be movable as the main unit 21 moves. In thismovable configuration, the first cut filter 30 may be moved togetherwith the main unit 21 by the robot arm unit 60.

It will be sufficient for the first cut filter 30 to have a role ofpartly or wholly blocking the wavelength range of fluorescent beams FBemitted from the semiconductor laser unit 20A before welding. Therefore,the first cut filter 30 may be disposed not only on the outside of thesemiconductor laser unit 20A separately therefrom, but also within thesemiconductor laser unit 20A as long as it is positioned closer to thewelding areas DA, UA than is the optical means partly or whollygenerating the wavelength range of fluorescent beams FB. Preferably, thefirst cut filter 30 is disposed at a position where the luminous flux oflaser beams LB is widened (energy density is lower) This is because thesemiconductor laser unit 20A has such a high output that the energydensity is higher at a position where the laser beams LB are converged,whereby the first cut filter 30 is damaged by heat.

The second cut filter 40 will now be explained with reference to FIGS.9, 10, and 11 as well. FIG. 9 is a chart showing the relationshipbetween wavelength and intensity of light radiating from the weldingareas DA, UA. FIG. 10 is a chart showing the relationship between thewavelength and transmittance as a characteristic of the second cutfilter. FIG. 11 is a chart showing the relationship between wavelengthand intensity of light obtained after the light radiating from thewelding areas DA, UA is transmitted through the second cut filter 40.

The second cut filter 40 is a filter which blocks the laser beams LBhaving the oscillation wavelength emitted from the semiconductor laserunit 20A in the light radiating from the welding areas DA, UA. FIG. 9,whose abscissa and ordinate indicate the wavelength and intensity oflight, respectively, shows the light radiating from the welding areasDA, UA. As can be seen from FIG. 9, the welding areas DA, UA partlyreflect the laser beams LB having the oscillation wavelength emittedfrom the semiconductor laser unit 20A, while generating thermallyradiating beams RB. The laser beams LB having the oscillation wavelengthfrom the welding areas DA, UA become noises when detecting the weldingtemperature of the welding areas. DA, UA. Therefore, as shown in FIG.10, the second cut filter 40 has a property of transmitting therethroughlight having a wavelength longer than 1100 nm in order to reliablytransmit the thermally radiating beams RB therethrough and block thelaser beams. LB having the oscillation wavelength of 810 nm. When thelight radiating from the welding areas DA, UA enters the second cutfilter 40 having such a property, only the thermally radiating beams RBpass therethrough as shown in FIG. 11. In each of FIGS. 9 and 11, theabscissa and ordinate indicate the wavelength and intensity of light,respectively.

The second cut filter 40 is disposed between the upper resin member URand a light-collecting part 51 of the resin temperature measuring unit50A, and is configured so as to be movable as the welding positionmoves. In this movable configuration, the second cut filter 40 may bemoved together with the main unit 21 of the semiconductor laser unit 20Aby the robot arm unit 60.

The resin temperature measuring unit 50A is a radiation thermometerwhich measures the welding temperature by using the thermally radiatingbeams RB from the welding areas DA, UA. Here, the resin temperaturemeasuring unit 50A may be a monochromatic radiation thermometer whichdetects the temperature according to light having a single observationwavelength (e.g., 1800 nm) in the thermally radiating beams RB, or apolychromatic radiation thermometer which detects the temperatureaccording to a plurality of observation wavelengths (e.g., twowavelengths of 1800 nm and 2000 nm) of light in the thermally radiatingbeams RB.

The resin temperature measuring unit 50A comprises the light-collectingpart 51, an optical fiber 52, and a temperature detecting part 53. Thelight-collecting part 51 collects the thermally radiating beams RBtransmitted through the second cut filter 40 from the welding areas DA,UA. Therefore, the light-collecting part 51 is disposed at a positionwhere the thermally radiating beams RB are reliably received, and isconfigured so as to be movable as the welding position moves. In thismovable configuration, the light-collecting part 51 may be movedtogether with the main unit 21 of the semiconductor laser unit 20A bythe robot arm unit 60. The optical fiber 52 transmits the thermallyradiating beams RB collected by the light-collecting part 51 to thetemperature detecting part 53. The resin temperature measuring unit 50Aalso has a function of detecting the welding position.

The temperature detecting part 53 turns the thermally radiating beams RBtransmitted and collected by the optical fiber 50 into collimated light,and extracts at least one observation wavelength light component fromthus collimated light. Then, in the temperature detecting part 53, theindividual observation wavelength light components are collected andmade incident on an infrared detector, which photoelectrically convertseach observation wavelength light component into an electric signal.Further, the temperature detecting part 53 calculates the weldingtemperature according to the electric signal of each observationwavelength.

The robot arm unit 60 is a unit which controls the focal position of thelaser beams LB, the welding position, the welding speed, etc., andthree-dimensionally moves the main unit 21 of the semiconductor laserunit 20A. The robot arm unit 60 may be configured such as to move thefirst cut filter 30, the second cut filter 40, and the light-collectingpart 51 of the resin temperature measuring unit 50A three-dimensionally.

The robot arm unit 60 comprises a leading end part 61, an arm part 62,and a controller 63. The leading end part 61 has the main unit 21 and,when necessary, the first cut filter 30, second cut filter 40, andlight-collecting part 51 attached thereto, and three-dimensionally movesthe main unit 21, etc., according to operations of the arm part 62. Thearm part 62 is a polyarticular arm which three-dimensionally moves theleading end part 61 according to a control signal from the controller63. According to an instruction signal from the control unit 70, thecontroller 63 sends a control signal for moving the leading part 61 tothe arm part 62.

The control unit 70 is a unit which integrally manages the resin weldingapparatus 1A, and is connected to the controller 14 of the pressureapplying unit 10, the controller 22 of the semiconductor laser unit 20A,the temperature detecting unit 53 of the resin temperature measuringunit 50A, and the controller 63 of the robot arm unit 60.

According to the welding temperature detected by the resin temperaturemeasuring unit 50A, the control unit 70 regulates irradiation conditionsof the semiconductor laser unit 20A (intensity, focus diameter, etc.),the focal position of the laser beams LB, the welding speed, etc. Tothis aim, the control unit 70 receives a signal indicative of thewelding temperature detected from the temperature detecting part 53, andsends instruction signals to the controllers 22 and 63. According to thedetected pressure between the upper resin member UR and lower resinmember DR from a pressure sensor (not depicted), the control unit 70controls the regulator 13 of the pressure applying unit 10 such that thepressure falls within a predetermined pressure range. Therefore, thecontrol unit 70 receives a signal indicative of the detected pressurefrom the pressure sensor (not depicted) and sends an instruction signalto the controller 14.

The control unit 70 stores therein relationships between resin membersUR, DR in a number of combinations and reference temperature ranges, andsets the reference temperature range according to two resin members UR,DR to be welded. The reference temperature range is set within a rangeof not higher than the welding temperature of the upper resin member URand lower resin member DR, but not higher than their decompositiontemperatures. The control unit 70 also stores therein relationshipsbetween resin members UR, DR in a number of combinations and referencepressure ranges, and sets the reference pressure range according to tworesin members UR, DR to be welded. The control unit 70 further storesrelationships between the resin members UR, DR and the weldingtemperature and pressure during welding. After welding, the control unit70 reflects data concerning the welding temperature and pressure at thetime of defective welding and the welding temperature and pressure atthe time of favorable welding onto the reference temperature range,reference pressure range, irradiation conditions, etc., thereby furtherlowering the ratio of defective welding.

Operations of the resin welding apparatus 1A will now be explained withreference to FIGS. 1 to 11.

First, the lower resin member DR and upper resin member UR are stackedon each other and set to a predetermined position of the base plate 11.Then, in the resin welding apparatus 1A, the pressure applying unit 10applies a pressure between the lower resin member DR and upper resinmember UR according to an instruction from the control unit 70. Also, inthe resin welding apparatus 1A, the robot arm unit 60 moves the mainunit 21 of the semiconductor laser unit 20A and the like to theirinitial positions according to an instruction from the control unit 70.Then, in the resin welding apparatus 1A, the semiconductor laser unit20A emits laser beams LB such that the welding temperature falls withina reference temperature range according to an instruction from thecontrol unit 70.

Here, the semiconductor laser unit 20A emits not only the laser beams LBhaving the oscillation wavelength, but also the fluorescent beams FBgenerated by the first collimating lenses 21 b, second collimating lens21 c, and condenser lens 21 d (see FIG. 6). However, the fluorescentbeams FB are blocked by the first cut filter 30. Therefore, only thelaser beams LB having the oscillation wavelength transmitted through thefirst cut filter 30, pressure plate 12, and upper resin member UR reachthe welding area DA of the lower resin member DR (see FIG. 8).

The laser beams LB having reached the welding area DA are absorbedthereby, whereby the welding area DA is heated and melted. This heatfurther heats and melts the welding area UA of the upper resin memberUR, whereby the upper resin member UR and lower resin member DR arewelded together. Here, the welding areas DA, UA generate thermallyradiating beams RB and partly reflect the laser beams LB (see FIG. 9).

However, the laser beams LB reflected by the welding areas DA, UA areblocked by the second cut filter 40. Therefore, only the thermallyradiating beams RB transmitted through the second cut filter 40 reachthe light-collecting part 51 of the resin temperature measuring unit 50A(see FIG. 11). Namely, no light to become noise to the thermallyradiating beams RB is incident on the light-collecting part 51 at all.

Therefore, the resin temperature measuring unit 50A detects a stablewelding temperature with a high accuracy according to the thermallyradiating beams RB alone. Then, according to the welding temperaturewith a high accuracy, the control unit 70 controls irradiationconditions (intensity, focus diameter, etc.) of the semiconductor laserunit 20A, the local position of the laser beams LB set by the robot armunit 60, the welding speed, etc. Also, according to the pressuredetected by the pressure sensor (not depicted), the control unit 70controls the pressure between the resin members DR, UR caused by thepressure applying unit 10. The resin welding apparatus 1A emits thelaser beams LB and applies a pressure between the resin members DR, URaccording to thus controlled irradiation conditions, focal position,welding speed, pressure, etc., thereby performing stable welding at apressure within the reference pressure range and a welding temperaturewithin the reference temperature range, while changing the weldingposition.

In the resin welding apparatus 1A in accordance with the firstembodiment, the first cut filter 30 reliably removes the fluorescentbeams FB generated by optical means, which become noise light whendetecting the welding temperature, before they are incident on thewelding area DA, whereby the resin temperature measuring unit 50A candetect the welding temperature with a high accuracy. Therefore, theresin welding apparatus 1A can stably control the welding temperature,thereby lowering the ratio of defective welding. Also, the resin weldingapparatus 1A can improve the accuracy in detecting the weldingtemperature by a simple configuration in which only the first cut filter30 is added to a conventional configuration.

SECOND EMBODIMENT

A second embodiment will now be explained. With reference to FIG. 12,the configuration of a resin welding apparatus 1B will be explained.FIG. 12 is an overall diagram of the resin welding apparatus 1B inaccordance with the second embodiment. In the second embodiment,constituents similar to those in the resin welding apparatus 1A inaccordance with the first embodiment will be referred to with numeralsidentical thereto without repeating their overlapping explanations.

The resin welding apparatus 1B is an apparatus which controls thewelding temperature so as to make it fall within a reference temperaturerange, and welds an upper resin member UR and a lower resin member DR,which are welding members, to each other in a stacked fashion whilepressing them. To this aim, the resin welding apparatus 1B comprises apressure applying unit 10, a semiconductor laser unit 20B, a first cutfilter 30, a second cut filter 40, a resin temperature measuring unit50A, a robot arm unit 60, and a control unit 70. The resin weldingapparatus 1B differs from the resin welding apparatus 1A in accordancewith the first embodiment only in that the configuration of thesemiconductor laser unit 20B is of fiber-out type.

The semiconductor laser unit 20B will be explained with reference toFIG. 13 as well. FIG. 13 is a side view of the semiconductor laser unit20B and first cut filter 30.

The semiconductor laser unit 20B irradiates a welding area DA with laserbeams LB (having an oscillation wavelength of 810 nm), so as to heat andmelt the upper resin member UR and lower resin member DR. To this aim,the semiconductor laser unit 20B comprises a main unit 23, an opticalfiber 24, an emitting part 25, and a controller 22. The main unit 23generates laser beams LB according to a control signal from thecontroller 22, converges thus generated laser beams LB, and emits themto the optical fiber 24. The optical fiber 24 transmits the laser beamsLB from the main unit 23 to the emitting part 25. The emitting part 25collects the laser beams LB transmitted by the optical fiber 24, andemits them toward the welding area DA. According to instruction signalsfrom the control unit 70, the controller 22 sends control signals forregulating irradiation conditions (intensity, focus diameter, etc.) tothe main unit 23.

As with the main unit 21 in accordance with the first embodiment, themain unit 23 comprises a semiconductor laser 21 a, first collimatinglenses 21 b, . . . , a second collimating lens 21 c, and a condenserlens 21 d. In the main unit 23, as in the main unit 21, the laser lightemission points 21 i emit respective laser beams LB, which are thenconverged by the first collimating lenses 21 b, second collimating lens21 c, and condenser lens 21 d. However, unlike the main unit 21, themain unit 23 makes thus converged laser beams LB incident on the opticalfiber 24 instead of emitting them toward the welding area DA.

The emitting part 25 comprises a collimating lens 25 a and a condenserlens 25 b. The collimating lens 25 a is arranged perpendicularly to theemitting direction of the laser beams LB transmitted through the opticalfiber 24. The collimating lens 25 a turns the laser beams LB transmittedthrough the optical fiber 24 into parallel light. The condenser lens 25b is arranged in front of the collimating lens 25 a in the emittingdirection of laser beams LB while in parallel with the collimating lens25 a. The condenser lens 25 b has a predetermined focal length, andconverges parallel light onto a focal point (welding area DA). In thesecond embodiment, the collimating lens 25 a and condenser lens 25 b inthe emitting part 25 also generate fluorescent beams FB.

As in the foregoing, the semiconductor laser unit 20B is a high-outputlaser unit which emits a number of laser beams LB from the respectivelaser light emission points 21 i and collects the laser beams LB. Thesemiconductor laser unit 20A is of fiber-out type in which the main unit23 converges the laser beams LB, and thus converged laser beams LB aretransmitted through the optical fiber 24 and emitted from the, emittingpart 25 to the welding area DA. In the semiconductor laser unit 20B, thevertical position of the emitting part 25 is movable by the robot armunit 60, so that the focal position of the laser beams LB is adjusted.Also, in the semiconductor laser unit 20B, the horizontal position ofthe emitting part 25 is movable by the robot arm unit 60, so that thewelding speed and welding position are adjusted.

The first cut filter 30 is disposed at a position between the emittingpart 25 of the semiconductor laser unit 20B and the upper resin memberUR, where the laser beams LB and fluorescent beams FB acting asadditional light pass, and is configured so as to be movable as theemitting part 25 of the semiconductor laser unit 20B moves. It will besufficient for the first cut filter 30 to have a role of partly orwholly blocking the wavelength range of fluorescent beams FB emittedfrom the semiconductor laser unit. 20B before welding as mentionedabove. Therefore, the first cut filter 30 may be disposed not only onthe outside of the semiconductor laser unit 20B separately therefrom,but also within the semiconductor laser unit 20B as long as it ispositioned closer to the welding areas DA, UA than is the optical meanspartly or wholly generating the wavelength range of fluorescent beamsFB.

Operations of the resin welding apparatus 1B will now be explained withreference to FIGS. 12 and 13.

First, the lower resin member DR and upper resin member UR are stackedon each other and set to a predetermined position of the base plate 11.Then, in the resin welding apparatus 1B, the pressure applying unit 10applies a pressure between the lower resin member DR and upper resinmember UR according to an instruction from the control unit 70. Also, inthe resin welding apparatus 1B, the robot arm unit 60 moves the emittingpart 25 of the semiconductor laser unit 20B and the like to theirinitial positions according to an instruction from the control unit 70.Then, in the resin welding apparatus 1B, the semiconductor laser unit20B emits laser beams LB such that the welding temperature falls withina reference temperature range according to an instruction from thecontrol unit 70.

Here, in the semiconductor laser unit 20B, the laser beams LB generatedand converged by the main unit 23 are made incident on the optical fiber24. Then, in the semiconductor laser unit 20B, the laser beams LB aretransmitted to the emitting part 25 through the optical fiber 24, andconverged and emitted by the emitting part 25.

Operations after the laser beams LB are emitted from the semiconductorlaser unit 20B in the resin welding apparatus 1B are the same as thosein the resin welding apparatus 1A in accordance with the firstembodiment and thus will not be explained. In the second embodiment, notonly the first collimating lenses 21 b, second collimating lens 21 c,and condenser lens 21 d, but also the collimating lens 25 a andcondenser lens 25 b in the emitting part 25 generate the fluorescentbeams FB, which are also emitted from the emitting part 25.

The resin welding apparatus 1B in accordance with the second embodimentnot only yields the effects of the resin welding apparatus 1A inaccordance with the first embodiment, but also can save the space foremitting the laser beams LB, since the emitting part 25 is constructedseparately from the main unit 23 in the semiconductor laser unit 20B.

THIRD EMBODIMENT

A third embodiment will now be explained. With reference to FIG. 14, theconfiguration of a resin welding apparatus 1C will be explained. FIG. 14is an overall diagram of the resin welding apparatus 1C in accordancewith the third embodiment. In the third embodiment, constituents similarto those in the resin welding apparatus 1A in accordance with the firstembodiment will be referred to with numerals identical thereto withoutrepeating their overlapping explanations.

The resin welding apparatus 1C is an apparatus which controls thewelding temperature so as to make it fall within a reference temperaturerange, and welds an upper resin member UR and a lower resin member DR,which are welding members, to each other in a stacked fashion whilepressing them. To this aim, the resin welding apparatus 1C comprises apressure applying unit 10, a semiconductor laser unit 20C, a resintemperature measuring unit 50C, a robot arm unit 60, and a control unit70. The resin welding apparatus 1C differs from the resin weldingapparatus 1A in accordance with the first embodiment in that a coatingapplied to optical means of the semiconductor laser unit 20C blocks apart of wavelength light components of the fluorescent beams FB insteadof blocking the fluorescent beams FB by using the first cut filter 30.

The semiconductor laser unit 20C will now be explained with reference toFIGS. 15, 16, and 17 as well. FIG. 15 is a side view of thesemiconductor laser unit 20C. FIG. 16 is a chart showing therelationship between wavelength and transmittance as a characteristic ofa coating 26 b of a condenser lens 26 a. FIG. 17 is a chart showing therelationship between wavelength and intensity of light obtained afterthe light emitted from the semiconductor laser unit 20C is transmittedthrough the condenser lens 26 a.

The semiconductor laser unit 20C irradiates a welding area DA with laserbeams LB (having an oscillation wavelength of 810 nm), so as to heat andmelt the upper resin member UR and lower resin member DR. To this aim,the semiconductor laser unit 20C comprises a main unit 26 and acontroller 22. The main unit 26 generates the laser beams LB accordingto a control signal from the controller 22, converges thus generatedlaser beams LB, and emits them toward the welding area DA. According toinstruction signals from the control unit 70, the controller 22 sendscontrol signals for regulating irradiation conditions (intensity, focusdiameter, etc.) to the main unit 26.

The main unit 26 comprises a semiconductor laser 21 a, first collimatinglenses 21 b, . . . , a second collimating lens 21 c, and a condenserlens 26 a. The main unit 26 differs from the main unit 21 in accordancewith the first embodiment only in the condenser lens 26 a, whereby onlythe condenser lens 26 a will be explained. Here, the first collimatinglenses 21 b and second collimating lens 21 c constitute first opticalmeans for converging the laser beams LB generated by the semiconductorlaser 21 a onto the welding area DA, whereas the condenser lens 26 a issecond optical means for blocking a part of the wavelength range offluorescent beams FB generated by the first optical means.

The condenser lens 26 a is arranged in front of the second collimatinglens 21 c in the emitting direction of the laser beams LB. The condenserlens 26 a has a predetermined focal length, and converges parallel lightonto a focal point (welding area DA) For suppressing the reflectionloss, the surface of the condenser lens 26 a is provided with anantireflection coating 26 b. This antireflection coating 26 is not acoating fully taking account of the wavelength region other than theoscillation wavelength of the laser beams LB, and thus has a property ofblocking wavelength light beams FB1 in a part of fluorescent beams. FBgenerated by the first collimating lenses 21 b and second collimatinglens 21 c. FIG. 16, whose abscissa and ordinate indicate the wavelengthand transmittance of light, respectively, shows a transmissioncharacteristic (solid line) of the coating 26 b. As can be seen fromFIG. 16, the coating 26 b has a property of reliably transmitting thelaser beams LB having the oscillation wavelength of 810 nm therethroughand blocking the light beams FB1 (hereinafter referred to ascoating-blocked fluorescent beams) within a partial wavelength range(1600 nm to 1900 nm) of the fluorescent beams. FB acting as additionallight. When the laser beams LB having the oscillation wavelength andfluorescent beams FB emitted from semiconductor laser 21 a enter thecondenser lens 26 a provided with the coating 26 b having such aproperty, light beams FB2 (hereinafter referred to ascoating-transmitted fluorescent beams) excluding a partial wavelengthrange (1600 nm to 1900 nm) from the laser light beams LB having theoscillation wavelength and fluorescent beams FB are transmittedtherethrough as shown in FIG. 17. In FIG. 17, the abscissa and ordinateindicate the wavelength and intensity of light, respectively.

Though the condenser lens 26 a also generates fluorescent beams FB, itwill be sufficient if the wavelength range of the fluorescent beams FBgenerated by the condenser lens 26 a is not used by the resintemperature measuring unit 50C. Though the condenser lens 26 a isprovided with the coating 26 b here, a coating having a property ofblocking a partial wavelength range of the fluorescent beams FBgenerated by the first collimating lens 21 b may be applied to thesecond collimating lens 21 c as well.

The main unit 26 generates a voltage between the planar electrodes 21 e,21 f according to a control signal from the controller 22, and emits thelaser beams LB from the respective laser light emission points 21 iaccording to this voltage. In the main unit 26, the laser beams LBemitted from the respective laser light emission points 21 i are turnedinto parallel beams with respect to the latitudinal directions of thelaser arrays 21 h by the first collimating lenses 21 b, and then areturned into parallel beams with respect to the longitudinal directionsof the laser arrays 21 h by the second collimating lens 21 c. Finally,in the main unit 26, the laser beams LB turned into parallel beams areconverged onto the welding area DA by the condenser lens 26 b. Here,since the condenser lens 26 a is provided with the coating 26 b, themain unit 26 does not emit the light beams FB1 within the wavelengthrange of 1600 nm to 1900 nm. Therefore, no noise light will mingle intothermally radiating beams RB if the wavelength range of 1600 nm to 1900nm is employed as an observation wavelength in the resin temperaturemeasuring unit 50C.

The resin temperature measuring unit 50C will now be explained withreference to FIGS. 18, 19, and 20 as well. FIG. 18 is a chart showingrelationships between wavelength and intensity of light radiating fromthe welding areas DA, UA. FIG. 19 is a chart showing the relationshipbetween wavelength and transmittance as a characteristic of a bandpassfilter 54 a. FIG. 20 is a chart showing the relationship betweenwavelength and intensity of light obtained after light radiating fromthe welding areas DA, UA is transmitted through the bandpass filter 54a.

The resin temperature measuring unit 50C is a radiation thermometerwhich measures the welding temperature by using thermally radiatingbeams RB from the welding areas DA, UA. Here, the resin temperaturemeasuring unit 50C may be a monochromatic radiation thermometer whichdetects the temperature according to light having a single observationwavelength in the thermally radiating beams RB, or a polychromaticradiation thermometer which detects the temperature according to aplurality of observation wavelengths of light in the thermally radiatingbeams RB. The observation wavelength range is restricted in the resintemperature measuring unit 50C in particular to the range of 1600 nm to1900 nm blocked by the coating applied to the condenser lens 26 a of thesemiconductor laser unit 20C.

The resin temperature measuring unit 50C comprises a light-collectingpart 51, an optical fiber 52, and a temperature detecting part 54. Theresin temperature measuring unit 50C differs from the resin temperaturemeasuring unit 50A in accordance with the first embodiment only in thetemperature detecting part 54, whereby only the temperature detectingpart 54 will be explained. FIG. 18, whose abscissa and ordinate indicatethe wavelength and intensity of light, respectively, shows lightradiating from the welding areas DA, UA. As can be seen from FIG. 18,the welding areas DA, UA reflect a part of the laser beams LB having theoscillation wavelength emitted from the semiconductor laser unit 20C anda part of the coating-transmitted fluorescent beams FB2, whilegenerating thermally radiating beams RB. The laser beams LB having theoscillation wavelength and coating-transmitted fluorescent beams FB2from the welding areas DA, UA become noises when detecting the weldingtemperature of the welding areas DA, UA. Therefore, in the resintemperature measuring unit 50C, the laser beams LB having theoscillation wavelength and coating-transmitted fluorescent beams FB2 areremoved by the temperature detecting part 54.

To this aim, the temperature detecting part 54 is equipped with thebandpass filter 54 a. The bandpass filter 54 a is a filter which isdisposed at a position where the light transmitted through the opticalfiber 52 is received, and transmits therethrough only the thermallyradiating beams RB1 corresponding to the wavelength range (1600 nm to1900 nm) blocked by the coating 26 b of the semiconductor laser unit 20Cin the light transmitted through the optical fiber 52 after havingradiated from the welding areas DA, UA. As shown in FIG. 19, thebandpass filter 54 a has a property of reliably transmittingtherethrough the thermally radiating beams RB1 (hereinafter referred toas bandpass-filter-transmitted thermally radiating beams) within thewavelength range slightly longer on the shorter wavelength side andshorter on the longer wavelength side than the wavelength range (1600 nmto 1900 nm) blocked by the coating 26 b. When the light radiating fromthe welding areas DA, UA enters the bandpass filter 54 a having such aproperty, only the thermally radiating beams RB1 within the wavelengthrange slightly longer on the shorter wavelength side and shorter on thelonger wavelength side than the wavelength range of 1600 nm to 1900 nmare transmitted therethrough. In each of FIGS. 19 and 20, the abscissaand ordinate indicate the wavelength and intensity of light,respectively.

The temperature detecting part 54 turns the bandpass-filter-transmittedthermally radiating beams RB1 transmitted through the bandpass filter 54a into collimated light, and then extracts at least one observationwavelength light component from thus collimated light. The observationwavelength is set to a wavelength within the wavelength rangetransmitted through the bandpass filter 54 a. Then, in the temperaturedetecting part 54, the individual observation wavelength lightcomponents are collected and made incident on an infrared detector,which photoelectrically converts each observation wavelength lightcomponent into an electric signal. Further, the temperature detectingpart 54 calculates the welding temperature according to the electricsignal of each observation wavelength.

Operations of the resin welding apparatus 1C will now be explained withreference to FIGS. 14 to 20.

First, the lower resin member DR and upper resin member UR are stackedon each other and set to a predetermined position of the base plate 11.Then, in the resin welding apparatus 1C, the pressure applying unit 10applies a pressure between the lower resin member DR and upper resinmember UR according to an instruction from the control unit 70. Also, inthe resin welding apparatus 1C, the robot arm unit 60 moves the mainunit 26 of the semiconductor laser unit 20C and the like to theirinitial positions according to an instruction from the control unit 70.Then, in the resin welding apparatus 1C, the semiconductor laser unit20C emits laser beams LB such that the welding temperature falls withina reference temperature range according to an instruction from thecontrol unit 70.

Here, the semiconductor laser unit 20C generates not only the laserbeams LB having the oscillation wavelength, but also the fluorescentbeams FB caused by the first collimating lenses 21 b, second collimatinglens 21 c, and condenser lens 26 a. However, in the semiconductor laserunit 20C, the coating 26 b of the condenser lens 26 a blocks the lightbeams FB1 within a partial wavelength range of the fluorescent beams FB.Therefore, the laser beams LB having the oscillation wavelengthtransmitted through the coating 26 b, pressure plate 12, and upper resinmember UR and the fluorescent beams FB2 transmitted through the coatingreach the welding area DA of the lower resin member DR (see FIG. 17).

The laser beams LB having reached the welding area DA are absorbedthereby, whereby the welding area DA is heated and melted. This heatfurther heats and melts the welding area UA of the upper resin memberUR, whereby the upper resin member UR and lower resin member DR arewelded together. Here, the welding areas DA, UA generate thermallyradiating beams RB and partly reflect the laser beams LB andcoating-transmitted fluorescent beams FB2 (see FIG. 18).

Then, in the resin temperature measuring unit 50C, the thermallyradiating beams RB, laser beams LB, and coating-transmitted fluorescentbeams FB2 reach the light-collecting part 51, and are transmittedthrough the optical fiber 52 to the temperature detecting part 54. Inthe temperature detecting part 54, the bandpass filter 54 a blocks thelaser beams LB, coating-transmitted fluorescent beams FB2, and a part ofthe thermally radiating beams RB, so that only thebandpass-filter-transmitted thermally radiating beams RB1 aretransmitted therethrough. Namely, the bandpass filter 54 a removes lightto become noises.

Therefore, the temperature detecting part 54 detects a stable weldingtemperature with a high accuracy according to thebandpass-filter-transmitted thermally radiating beams RB1 alone. Then,according to the welding temperature with a high accuracy, the controlunit 70 controls irradiation conditions (intensity, focus diameter,etc.) of the semiconductor laser unit 20C, the focal position of thelaser beams LB set by the robot arm unit 60, the welding speed, etc.Also, according to the pressure detected by a pressure sensor (notdepicted), the control unit 70 controls the pressure between the resinmembers DR, UR caused by the pressure applying unit 10. The resinwelding apparatus 1C emits the laser beams LB and applies a pressurebetween the resin members DR, UR according to thus controlledirradiation conditions, focal position, welding speed, pressure, etc.,thereby performing stable welding at a pressure within the referencepressure range and a welding temperature within the referencetemperature range, while changing the welding position.

In the resin welding apparatus 1C in accordance with the thirdembodiment, light beams within a partial wavelength range of thefluorescent beams FB generated by the first optical means, which becomenoise light when detecting the welding temperature, are removed by thecoating 26 b applied to the condenser lens 26 a before being madeincident on the welding area DA, whereby the resin temperature measuringunit 50C can detect the welding temperature with a high accuracy.Therefore, the resin welding apparatus 1C stabilizes the control of thewelding temperature, and lowers the ratio of defective welding. Also,since the coating 26 b usually applied to the optical means of thesemiconductor laser unit 20C partly blocks the fluorescent beams FB, theresin welding apparatus 1C does not separately need a cut filter or thelike. Therefore, the resin welding apparatus 1C can improve the accuracyin detecting the welding temperature at low cost.

FOURTH EMBODIMENT

A fourth embodiment will now be explained. The resin welding apparatus1D in accordance with the fourth embodiment has the same configurationas with the resin welding apparatus 1A in accordance with the firstembodiment as shown in FIG. 1, and thus will not be explained in detail.However, the resin welding apparatus 1D in accordance with the fourthembodiment differs from the resin welding apparatus 1A in accordancewith the first embodiment in that light beams AB generated by thesemiconductor laser 21 a itself other than the oscillation wavelengthare blocked by a first cut filter 30 (i.e., the first embodimentsubstantially corresponds to the fourth embodiment if the “fluorescentbeams FB” in the explanation of the first embodiment are assumed to be“light beams AB other than the oscillation wavelength”) as shown in FIG.21.

This is because one of reasons why a semiconductor laser unit emitsadditional light (light components other than the oscillation wavelengthof the semiconductor laser in the light generated by the semiconductorlaser unit) is the generation of light other than the oscillationwavelength from the semiconductor laser itself. In particular, ahigh-output type semiconductor laser generates laser light beams from anumber of laser light emission points, and thus seems to yield lightbeams having various wavelengths. As a cause of the generation of suchlaser beams in this semiconductor laser, there is a possibility of lightbeing emitted from an impurity level or defect level within thesemiconductor. Namely, the semiconductor laser for welding has such ahigh output that its resonator has a size of 1 μm×100 μm, for example.If this resonator outputs a laser beam of 1 W, the laser power densitywill be at least 1 MW/cm². At such a laser power density, a lightcomponent other than the oscillation wavelength seems to be generatedfrom an impurity level, a defect level, or the like within thesemiconductor constituting the resonator.

For example, the semiconductor laser unit 20A in accordance with thefourth embodiment emits the laser beams LB having the oscillationwavelength (810 nm) and light beams AB other than the oscillationwavelength which are additional light as shown in FIG. 6. FIG. 6, whoseabscissa and ordinate indicate the wavelength and intensity of light,respectively, is a chart showing relationships between wavelength andintensity in laser light having the oscillation wavelength andadditional light (light other than the oscillation wavelength from thesemiconductor laser itself here) emitted from the semiconductor laserunit. Therefore, “additional light” in FIGS. 5 and 7 is “light otherthan the oscillation wavelength” in the fourth embodiment.

It will be sufficient for the first cut filter 30 to have a role ofblocking the light beams AB other than the oscillation wavelengthemitted from the semiconductor laser unit 20A before welding. Therefore,the first cut filter 30 may be disposed not only on the outside of thesemiconductor laser unit 20A separately therefrom, but also within thesemiconductor laser unit 20A. For example, the first cut filter 30 maybe disposed between the first collimating lenses 21 b and secondcollimating lens 21 c, between the second collimating lens 21 c and thecondenser lens 21 d, etc. Preferably, the first cut filter 30 isdisposed at a position where the luminous flux of laser beams LB iswidened (energy density is lower). This is because the semiconductorlaser unit 20A has such a high output that the energy density is higherat a position where the laser beams LB are converged, whereby the firstcut filter 30 is damaged by heat.

Operations of the resin welding apparatus 1D will now be explained withreference to FIGS. 1, 3 to 11, and 21.

First, the lower resin member DR and upper resin member UR are stackedon each other and set to a predetermined position of the base plate 11.Then, in the resin welding apparatus 1D, the pressure applying unit 10applies a pressure between the lower resin member DR and upper resinmember UR according to an instruction from the control unit 70. Also, inthe resin welding apparatus 1D, the robot arm unit 60 moves the mainunit 21 of the semiconductor laser unit 20A and the like to theirinitial positions according to an instruction from the control unit 70.Then, in the resin welding apparatus 1D, the semiconductor laser unit20A emits laser beams LB such that the welding temperature falls withina reference temperature range according to an instruction from thecontrol unit 70.

Here, the semiconductor laser unit 20A emits not only the laser beams LBhaving the oscillation wavelength, but also the light beams AB otherthan the oscillation wavelength (see FIG. 6). However, the light beamsAB other than the oscillation wavelength are blocked by the first cutfilter 30. Therefore, only the laser beams LB having the oscillationwavelength transmitted through the first cut filter 30, pressure plate12, and upper resin member UR reach the welding area DA of the lowerresin member DR (see FIG. 8).

The laser beams LB having reached the welding area DA are absorbedthereby, whereby the welding area DA is heated and melted. This heatfurther heats and melts the welding area UA of the upper resin memberUR, whereby the upper resin member UR and lower resin member DR arewelded together. Here, the welding areas DA, UA generate thermallyradiating beams RB and partly reflect the laser beams LB (see FIG. 9).

However, the laser beams LB reflected by the welding areas DA, UA areblocked by the second cut filter 40. Therefore, only the thermallyradiating beams RB transmitted through the second cut filter 40 reachthe light-collecting part 51 of the resin temperature measuring unit 50A(see FIG. 11). Namely, no light to become noise to the thermallyradiating beams RB is incident on the light-collecting part 51 at all.

Therefore, the resin temperature measuring unit 50A detects a stablewelding temperature with a high accuracy according to the thermallyradiating beams RB alone. Then, according to the welding temperaturewith a high accuracy, the control unit 70 controls irradiationconditions (intensity, focus diameter, etc.) of the semiconductor laserunit 20A, the focal position of the laser beams LB by the robot arm unit60, the welding speed, etc. Also, according to the pressure detected bya pressure sensor (not depicted), the control unit 70 controls thepressure between the resin members DR, UR caused by the pressureapplying unit 10. The resin welding apparatus 1D emits the laser beamsLB and applies a pressure between the resin members DR, UR according tothus controlled irradiation conditions, focal position, welding speed,pressure, etc., thereby performing stable welding at a pressure withinthe reference pressure range and a welding temperature within thereference temperature range, while changing the welding position.

In the resin welding apparatus 1D in accordance with the fourthembodiment, the first cut filter 30 reliably removes the light beams ABother than the oscillation wavelength, which become noise light whendetecting the welding temperature, before they are incident on thewelding area DA, whereby the resin temperature measuring unit 50A candetect the welding temperature with a high accuracy. Therefore, theresin welding apparatus 1D can stably control the welding temperature,thereby lowering the ratio of defective welding. Also, the resin weldingapparatus 1D can improve the accuracy in detecting the weldingtemperature by a simple configuration in which only the first cut filter30 is added to a conventional configuration.

FIFTH EMBODIMENT

A fifth embodiment will now be explained. The resin welding apparatus 1Ein accordance with the fifth embodiment has the same configuration aswith the resin welding apparatus 1B in accordance with the secondembodiment as shown in FIG. 12, and thus will not be explained indetail. However, the resin welding apparatus 1E in accordance with thefifth embodiment differs from the resin welding apparatus 1B inaccordance with the second embodiment in that light beams AB generatedby the semiconductor laser 21 a itself other than the oscillationwavelength are blocked by a first cut filter 30 (i.e., the secondembodiment substantially corresponds to the fifth embodiment if the“fluorescent beams FB” in the explanation of the second embodiment areassumed to be “light beams AB other than the oscillation wavelength”) asshown in FIG. 22.

The first cut filter 30 in accordance with the fifth embodiment isdisposed at a position between the emitting part 25 of the semiconductorlaser unit 20B and the upper resin member UR, where the laser beams LBand light beams AB acting as additional light pass, and is configured soas to be movable as the emitting part 25 of the semiconductor laser unit20B moves. It will be sufficient for the first cut filter 30 to have arole of blocking the light beams AB emitted from the semiconductor laserunit 20B other than the oscillation wavelength before welding asmentioned above. Therefore, the first cut filter 30 may be disposed notonly on the outside of the semiconductor laser unit 20B separatelytherefrom, but also within the semiconductor laser unit 20B. Forexample, the first cut filter 30 may be disposed between the firstcollimating lenses 21 b and second collimating lens 21 c, between thesecond collimating lens 21 c and condenser lens 21 d, between thecondenser lens 21 d and optical fiber 24, between the collimating lens25 a and condenser lens 25 b, etc.

Operations of the resin welding apparatus 1E will now be explained withreference to FIGS. 12 and 22.

First, the lower resin member DR and upper resin member UR are stackedon each other and set to a predetermined position of the base plate 11.Then, in the resin welding apparatus 1E, the pressure applying unit 10applies a pressure between the lower resin member DR and upper resinmember UR according to an instruction from the control unit 70. Also, inthe resin welding apparatus 1E, the robot arm unit 60 moves the emittingpart 25 of the semiconductor laser unit 20B and the like to theirinitial positions according to an instruction from the control unit 70.Then, in the resin welding apparatus 1E, the semiconductor laser unit20B emits laser beams LB such that the welding temperature falls withina reference temperature range according to an instruction from thecontrol unit 70.

Here, in the semiconductor laser unit 20B, the laser beams LB generatedand converged by the main unit 23 are made incident on the optical fiber24. Then, in the semiconductor laser unit 20B, the laser beams LB aretransmitted to the emitting part 25 through the optical fiber 24, andconverged and emitted by the emitting part 25.

Operations after the laser beams LB are emitted from the semiconductorlaser unit 20B in the resin welding apparatus 1E are the same as thosein the resin welding apparatus 1D in accordance with the fourthembodiment and thus will not be explained.

The resin welding apparatus 1E in accordance with the fifth embodimentnot only yields the effects of the resin welding apparatus 1D inaccordance with the fourth embodiment, but also can save the space foremitting the laser beams LB, since the emitting part 25 is constructedseparately from the main unit 23 in the semiconductor laser unit 20B.

SIXTH EMBODIMENT

A sixth embodiment will now be explained. The resin welding apparatus 1Fin accordance with the sixth embodiment has the same configuration aswith the resin welding apparatus 1C in accordance with the thirdembodiment as shown in FIG. 14, and thus will not be explained indetail. However, the resin welding apparatus 1F in accordance with thesixth embodiment differs from the resin welding apparatus 1C inaccordance with the third embodiment in that light beams AB generated bythe semiconductor laser 21 a itself other than the oscillationwavelength are blocked by a coating applied to the optical means in thesemiconductor laser unit 20 (i.e., the third embodiment substantiallycorresponds to the sixth embodiment if the “fluorescent beams FB” in theexplanation of the third embodiment are assumed to be “light beams ABother than the oscillation wavelength”) as shown in FIG. 23.

The condenser lens 26 a in accordance with the sixth embodiment isarranged in front of the second collimating lens 21 c in the emittingdirection of the laser beams LB. The condenser lens 26 a has apredetermined focal length, and converges parallel light onto a focalpoint (welding area DA). For suppressing the reflection loss, thesurface of the condenser lens 26 a is provided with an antireflectioncoating 26 b. This antireflection coating 26 is not a coating fullytaking account of the wavelength region other than the oscillationwavelength of the laser beams LB, and thus has a property of blockinglight beams AB1 in a part of the light beams AB other than theoscillation wavelength. As can be seen from FIG. 16, the coating 26 bhas a property of reliably transmitting the laser beams LB having theoscillation wavelength of 810 nm therethrough and blocking the lightbeams AB1 (hereinafter referred to as coating-blocked light beams otherthan the oscillation wavelength) within a partial wavelength range (1600nm to 1900 nm) of the light beams AB other than the oscillationwavelength acting as additional light. When the laser beams LB and lightbeams AB other than the oscillation wavelength emitted fromsemiconductor laser 21 a enter the condenser lens 26 a provided with thecoating 26 b having such a property, light beams AB2 (hereinafterreferred to as coating-transmitted light beams other than theoscillation wavelength) excluding a partial wavelength range (1600 nm to1900 nm) from the light beams AB other than the oscillation wavelengthare transmitted therethrough as shown in FIG. 17.

Though the condenser lens 26 is provided with the coating 26 b, thefirst collimating lenses 21 b and second collimating lens 21 c, whichare other optical means of the semiconductor laser unit 20C, may beprovided with a coating. The first collimating lenses 21 b, secondcollimating lens 21 c, and condenser lens 26 a constitute optical meansfor converging the laser light generated by the semiconductor laser 21 aonto the welding area DA.

Operations of the resin welding apparatus 1F will now be explained withreference to FIGS. 14, 16 to 20, and 23.

First, the lower resin member DR and upper resin member UR are stackedon each other and set to a predetermined position of the base plate 11.Then, in the resin welding apparatus 1F, the pressure applying unit 10applies a pressure between the lower resin member DR and upper resinmember UR according to an instruction from the control unit 70. Also, inthe resin welding apparatus 1F, the robot arm unit 60 moves the mainunit 26 of the semiconductor laser unit 20C and the like to theirinitial positions according to an instruction from the control unit 70.Then, in the resin welding apparatus 1C, the semiconductor laser unit20C emits laser beams LB such that the welding temperature falls withina reference temperature range according to an instruction from thecontrol unit 70.

Here, the semiconductor laser unit 20C generates not only the laserbeams LB having the oscillation wavelength, but also the light beams ABother than the oscillation wavelength. However, in the semiconductorlaser unit 20C, the coating 26 b of the condenser lens 26 a blocks thelight beams AB1 within a partial wavelength range of the light beams ABother than the oscillation wavelength. Therefore, the laser beams LBhaving the oscillation wavelength transmitted through the coating 26 b,pressure plate 12, and upper resin member UR and the coating-transmittedlight beams AB2 other than the oscillation wavelength reach the weldingarea DA of the lower resin member DR (see FIG. 17).

The laser beams LB having reached the welding area DA are absorbedthereby, whereby the welding area DA is heated and melted. This heatfurther heats and melts the welding area UA of the upper resin memberUR, whereby the upper resin member UR and lower resin member DR arewelded together. Here, the welding areas DA, UA generate thermallyradiating beams RB and partly reflect the laser beams LB andcoating-transmitted light beams AB2 other than the oscillationwavelength (see FIG. 18).

Then, in the resin temperature measuring unit 50C, the thermallyradiating beams RB, laser beams LB, and coating-transmitted light beamsFB2 other than the oscillation wavelength reach the light-collectingpart 51, and are transmitted through the optical fiber 52 to thetemperature detecting part 54. In the temperature detecting part 54, thebandpass filter 54 a blocks the laser beams LB, coating-transmittedlight beams AB2 other than the oscillation wavelength, and a part of thethermally radiating beams RB, so that only thebandpass-filter-transmitted thermally radiating beams RB1 aretransmitted therethrough. Namely, the bandpass filter 54 a removes lightto become noises.

Therefore, the temperature detecting part 54 detects a stable weldingtemperature with a high accuracy according to thebandpass-filter-transmitted thermally radiating beams RB1 alone. Then,according to the welding temperature with a high accuracy, the controlunit 70 controls irradiation conditions (intensity, focus diameter,etc.) of the semiconductor laser unit 20C, the focal position of thelaser beams LB set by the robot arm unit 60, the welding speed, etc.Also, according to the pressure detected by a pressure sensor (notdepicted), the control unit 70 controls the pressure between the resinmembers DR, UR caused by the pressure applying unit 10. The resinwelding apparatus 1F emits the laser beams LB and applies a pressurebetween the resin members DR, UR according to thus controlledirradiation conditions, focal position, welding speed, pressure, etc.,thereby performing stable welding at a pressure within the referencepressure range and a welding temperature within the referencetemperature range, while changing the welding position.

In the resin welding apparatus 1F in accordance with the sixthembodiment, light beams within a partial wavelength range of the lightbeams AB other than the oscillation wavelength, which become noise lightwhen detecting the welding temperature, are removed by the coating 26 bapplied to the condenser lens 26 a before being made incident on thewelding area DA, whereby the resin temperature measuring unit 50C candetect the welding temperature with a high accuracy. Therefore, theresin welding apparatus 1F stabilizes the control of the weldingtemperature, and lowers the ratio of defective welding. Also, since thecoating 26 b usually applied to the optical means of the semiconductorlaser unit 20C partly cuts the light beams AB other than the oscillationwavelength, the resin welding apparatus 1F does not separately need acut filter or the like. Therefore, the resin welding apparatus 1F canimprove the accuracy in detecting the welding temperature at low cost.

Though embodiments in accordance with the present invention areexplained in the foregoing, the present invention may be carried out invarious modes without being restricted to the above-mentionedembodiments.

For example, though the present invention is employed in welding resinmembers to each other in a stacked fashion, it may be employed in othertypes of resin welding such as welding of resin members to each other ina butting fashion, and in processing such as piercing and cutting otherthan the welding.

Though a first cut filter for blocking noise light is disposed on theoutside of the semiconductor laser unit in order to block thefluorescence generated by all the lenses in the optical means of thesemiconductor laser unit in the first to third embodiments, wavelengthcharacteristics of florescence of individual lenses in the optical meansmay be investigated, a first cut filter for blocking the wavelengthrange of the fluorescence of a specific lens in the optical means may bedisposed closer to the welding area than is the specific lens, and theobservation wavelength used in the resin temperature measuring apparatusmay be set within the wavelength range blocked by the first cut filter.When fluorescence wavelength ranges overlap among a plurality of lenses,the first cut filter is required to be disposed nearer to the weldingarea than are the plurality of lenses having the wavelengths overlappingeach other.

Though the first cut filter is constructed as a filter which totallyblocks the noise light in the above-mentioned embodiments, it may be afilter which blocks only the light within the observation wavelengthrange of 1100 nm to 2800 nm, or a filter which blocks only lightcomponents having a single observation wavelength or a plurality ofobservation wavelengths used in the resin temperature measuringapparatus.

Though the first and second collimating lenses are used in thesemiconductor laser units in the above-mentioned embodiments, otherlenses such as ball lenses may be used as well.

Though the coating applied to the condenser lens blocks light in apartial wavelength range of fluorescence in the third and sixthembodiment, means other than the coating applied to optical means of thesemiconductor laser units, e.g., transmission characteristics of opticallenses, may be used for blocking the fluorescence. Also, a fiber-outtype configuration may be used instead of the direct focusing type.

INDUSTRIAL APPLICABILITY

In the present invention, a light component having a wavelength tobecome an observation wavelength for detecting the processingtemperature in light generated by an optical system is blocked beforeprocessing, whereby no noise light mingles into thermally radiatinglight having the observation wavelength when detecting the processingtemperature. Therefore, the processing temperature can be detected witha high accuracy, and stable processing temperature control can reducedefective processing.

1. A laser processing apparatus for welding stacked resin members toeach other by using laser light, the apparatus comprising: asemiconductor laser for generating laser light; and a filter, disposedbetween the semiconductor laser and the resin members, for blockinglight having a wavelength that is other than an oscillation wavelengthof the semiconductor laser wherein said blocked light becomes anobservation wavelength for measuring a temperature of a welding area inthe light generated by the semiconductor laser; one of the stacked resinmembers, on the incident side of the laser light generated by thesemiconductor laser, having a property of transmitting the laser lightthat is generated by the semiconductor laser and the thermally radiatinglight that is generated by the welding area; the filter blocks the lightthat is generated by the semiconductor laser and that has a wavelengthother than an oscillation wavelength of the semiconductor laser, andsaid light having a wavelength falling within the range of 1500 nm to2800 nm which can be transmitted through the resin member on theincident side of the laser light; wherein the light that is generated bythe semiconductor laser and has a wavelength that cannot be blocked bythe filter is used for welding the resin members to each other, and saidthermally radiating light that is generated by the welding area and hasa wavelength that does not pass through said filter, said thermallyradiating light is used for measuring the temperature of the weldingarea.
 2. A laser processing apparatus for welding stacked resin membersto each other by using laser light, the apparatus comprising: asemiconductor laser for generating laser light; and optical means forconverging the laser light generated by the semiconductor laser onto awelding area and blocking light having a wavelength that is other thanan oscillation wavelength of the semiconductor laser wherein saidblocked light becomes an observation wavelength for measuring atemperature of the welding area in the light generated by thesemiconductor laser; one of the stacked resin members, on the incidentside of the laser light generated by the semiconductor laser, having aproperty of transmitting the laser light that is generated by thesemiconductor laser and the thermally radiating light that is generatedby the welding area; optical means blocks the light that is generated bythe semiconductor laser and that has a wavelength other than anoscillation wavelength of the semiconductor laser, and said light havinga wavelength falling within the range of 1500 nm to 2800 nm which can betransmitted through the resin member on the incident side of the laserlight; wherein the light that is generated by the semiconductor laserand has a wavelength that cannot be blocked by optical means is used forwelding the resin members to each other, and said thermally radiatinglight that is generated by the welding area and has a wavelength thatdoes not pass through said optical means, said thermally radiating lightis used for measuring the temperature of the welding area.
 3. A laserprocessing method for welding stacked resin members to each other byusing laser light, the method comprising: a laser light generating stepof causing a semiconductor laser to generate laser light; and afiltering step of blocking light having a wavelength that is other thanan oscillation wavelength of the semiconductor laser wherein saidblocked light becomes an observation wavelength for measuring atemperature of a welding area in the light generated by the laser lightgenerating step with a filter before welding; one of the stacked resinmembers, on the incident side of the laser light generated by the laserlight generating step, having a property of transmitting the laser lightthat is generated by the laser light generating step and the thermallyradiating light that is generated by the welding area; the filteringstep blocks the light that is generated by the laser light generatingstep and that has a wavelength other than an oscillation wavelength ofthe semiconductor laser, and said light having a wavelength fallingwithin the range of 1500 nm to 2800 nm which can be transmitted throughthe resin member on the incident side of the laser light; wherein thelight that is generated by the laser light generating step and has awavelength that cannot be blocked by the filtering step is used forwelding the resin members to each other, and said thermally radiatinglight that is generated by the welding area and has a wavelength thatdoes not pass through said filtering step, said thermally radiatinglight is used for measuring the temperature of the welding area.
 4. Alaser processing method for welding stacked resin members to each otherby using laser light, the method comprising: a laser light generatingstep of causing a semiconductor laser to generate laser light; and afiltering step of blocking light having a wavelength that is other thanan oscillation wavelength of the semiconductor laser wherein saidblocked light becomes an observation wavelength for measuring atemperature of a welding area in the light generated by the laser lightgenerating step with an optical system adapted to converge the laserlight generated by the laser light generating step onto the weldingarea; one of the stacked resin members, on the incident side of thelaser light generated by the laser light generating step, having aproperty of transmitting the laser light that is generated by the laserlight generating step and the thermally radiating light that isgenerated by the welding area; the filtering step blocks the light thatis generated by the laser light generating step and that has awavelength other than an oscillation wavelength of the semiconductorlaser, and said light having a wavelength falling within the range of1500 nm to 2800 nm which can be transmitted through the resin member onthe incident side of the laser light; wherein the light that isgenerated by the laser light generating step and has a wavelength thatcannot be blocked by the filtering step is used for welding the resinmembers to each other, and said thermally radiating light that isgenerated by the welding area and has a wavelength that does not passthrough said filtering step, said thermally radiating light is used formeasuring the temperature of the welding area.